As oil energy runs out, the solar cell technology development is one of the today's urgent things, nowaday many solar cells have been able to be mass-produced and applied. But because of the need to use a lot of area to absorb sunlight, the solar panels are so bulky, heavy and inconvenient for installation, resulting in its greatest weakness. If solar panels are applied on the building structure, they are usually placed on the roof which is of no use and the large area thereof can be exposed to the sun. In this way, not only the open space of the roof cannot be used for other purposes, but also if there are natural disasters such as typhoons, hurricanes and etc., the installed solar panels on the roof are blown away more easily leading to the public danger.
To solve the problem of a large area solar panel occupation and shading, a transparent solar cell has been booming in the development, if a transparent solar cell with a high optical transmittance is developed, the solar cells will be able to be installed in doors, windows and the likes of the general building. Generally windows and doors have the feature of a large area, and one of the window functions is the light transmittance. Therefore, if a high optical transmittance solar cell is developed and installed in windows and doors of the buildings, it not only solves the large area occupation and shading problem of the solar panels, but also provides a general building power source required.
In the current development, the negative type (n-type) transparent conductive oxide (TCO) has been able to achieve high conductivity, low resistivity, high optical transmittance and other requirements. However, the p-type transparent conductive oxide due to the material nature problems still cannot meet high conductivity, low resistivity, high optical transmittance requirements. For example, U. Kumar Barik et al. in “Electrical and optical properties of reactive DC magnetron sputtered silver oxide thin films: role of oxygen”, Thin Solid Thin Films 492 (2003) 129-134, disclosed silver oxide as a p-type transparent conductive oxide, which achieves the advantages of high hole mobility (6.1 cm2/V·s) and low resistivity (2.61×10−4 Ω·cm), but the transmittance of less than 2% was not in line with transparent requirements. And S. Golshahi et al. in “P-type ZnO thin film deposited by spray pyrolysis technique: The effect of solution concentration”, Thin Solid Thin Films 518 (2009) 1149-1152, disclosed a zinc oxide type transparent conductive oxide with the electron hole mobility of 6.31˜46.9 (cm2/V·s), and the optical transmittance of 60˜80%, but the impedance in the range of 0.66×100˜7.2×103 (Ω·cm), therefore, so far the technology can not yet meet high hole mobility, low resistivity and high optical transmittance requirements.